What does error code 33 mean on a Rinnai tankless water heater?

Heat exchanger thermistor. A fault with the heat exchanger temperature sensor.

Can I fix Rinnai code 33 myself?

Start with these safe checks: Note the code. Call a qualified technician.

When should I call a technician for code 33?

Call a qualified technician. Smell gas? Leave right away, don't touch light switches or phones inside, and call your gas utility or 911 from outside. Never open a gas valve, burner, gas line, vent or flue connection, or bypass a safety switch. Repeated lockouts, scorching, soot, or a CO alarm mean shut it off and call a licensed gas technician.

Rinnai tankless water heater error code

Rinnai tankless water heater code 33: Heat exchanger thermistor

Rinnai tankless water heaters

What 33 means

A fault with the heat exchanger temperature sensor.

Likely causes

Sensor or wiring fault

Safe first checks

Note the code.

When to stop

Call a qualified technician.

Checked against: Rinnai: Troubleshooting Tankless Water Heater Diagnostic Codes (100000652). Codes can differ by model and year, so confirm with your owner's manual.